Sensors are often used to monitor the position of one component relative to another. For example, a linear position sensor may be used to monitor the amount of extension of a hydraulic or pneumatic cylinder associated with a digging linkage. In another example, a rotary position sensor may be used to determine a pivot position, such as the amount of pivot of a control lever on the work machine.
Output signals of different sensors may vary for the same input. Additionally, output signals of a sensor can vary depending on its associated component. Accordingly, sensors should be calibrated in order to give a proper reading of the position of the monitored component. When used to monitor the extension of a cylinder, calibration may require that the cylinder be extended to a first position and a measurement taken of the sensor signal at the first position. Then, the cylinder may be retracted to a second position and a measurement taken of the sensor signal at the second position. By knowing the actual cylinder length at the first and second positions, and by knowing the signal output at the first and second positions, a linear scale or mapping may be used to determine the position of the cylinder for any given signal from the sensor.
Sometimes, the calibration process for a cylinder may occur at a cylinder manufacturing facility before the cylinder is installed on a work machine. The calibration information may be stored in a database. The cylinder and sensor then may be shipped to a work machine assembly plant, and the calibration information in the database may be sent separately, possibly via electronic means. Later, when the cylinder and sensor are to be installed on the work machine, the proper calibration information for the proper cylinder and sensor must be located and transferred to a control module on the work machine. However, such a system provides opportunities for error.
For example, it is possible that calibration information for one cylinder may be confused with calibration information from another cylinder. Accordingly, incorrect information may be uploaded to the control module on the work machine. If this occurs, the work machine does not have the proper calibration information for the cylinder and senor.
One known system for maintaining calibration information with a sensor is disclosed in U.S. Pat. No. 6,374,191 to Tsuchiya et al. The '191 patent discloses a pressure sensor that includes a memory and processor for determining calibration values. However, the pressure sensor does not store information specific to any system or component where it ultimately will be used. Therefore, the disclosed pressure sensor may not be usable in an environment where positions and/or displacement of a physical component are considered for proper calibration.
The disclosed system is directed to a position sensor that may overcome one or more of the deficiencies of the prior art.